How Alzheimer Disease (AD) and LBD Neuropathology Overlap

How Alzheimer Disease (AD) and LBD Neuropathology Overlap

After AD, LBD is the second most common cause of degenerative dementia. It is relatively new, only having been named in 1996. Caregivers have found that many LBD patients have been either misdiagnosed or the physician determined that the symptoms did not warrant further diagnosis or referral. Before 1996, cases were likely misdiagnosed because the developing clinical diagnostic criteria hadn't allowed even dementia specialists to reliably differentiate between AD and LBD. Hopefully, in the future, as the world becomes more aware of LBD, more patients will be referred to dementia specialists. Fortunately since 1996, the neuropathological diagnostic criteria have evolved greatly.

At present, neuropathologists are able to classify brains into four main categories when it comes to AD and LBD:

1. Pure AD (plaques & tangles, with no Lewy Bodies present)
2. AD (plaques & tangles present, with some Lewy Bodies-but not enough Lewy Bodies to believe the dementia syndrome was caused by them)
3. LBD (Lewy Bodies present, with some plaques & tangles-but not enough plaques and tangles to believe the dementia was caused by them)
4. Pure LBD (Lewy Bodies, with no plaques & tangles present).

With this overlap between pathologies the neuropathologists often require the clinical symptoms of LBD to be present in the history of the patient before being willing to classify a given brain in category #3 or #4 (above). This is a scientific weakness (although a relatively minor one)-- in that there isn't always exclusive independence between the neuropathological diagnosis and the clinical diagnosis (symptoms the patient exhibited while alive).

In looking at the cases that have been autopsy-confirmed over the past five years or so, you'll find that 90% of all dementia's are believed to be cause by AD (#1 or #2 above), 3-4% are caused by LBD (#3 or #4 above), 3-4% are caused by frontal-temporal dementia, and the remainder are caused by Parkinson's disease, Vascular disease, etc.

Of LBD cases collectively (#3 and #4 above), approx. 15% are 'Pure LBD cases (#4)' and 85% are 'LBD cases (#3)' So, of all dementia brains a neuropathologist analyzes, only (3% x 15%) = 0.45% are likely to be Pure LBD cases!

However, neuropathologists have said that in the totally 'normal' brains of non-demented elderly (90 to 100 year-olds), it is typical to find one or two Lewy Bodies if you search the brain carefully (but, that's nowhere near the number of Lewy Bodies found in LBD cases).

Differences Between Alzheimer's and Lewy Body Disease

1. PD symptoms are LBD, not AD; greater rigidity and fewer tremors; falls more common with LBD.
2. Hallucinations are LBD, not AD.
3. Cognitive fluctuations are LBD, not AD.
4. Short-term memory tends to be better with LBD, especially with Aricept or Exelon.
5. More severe visuospatial, visuoperceptual, and visuoconstruvctive problems, i.e. more trouble seeing things in space, understanding what they are, and how to deal with them.
6. PD and AD patients better able to manage the MMSE clock test and to learn from their errors on it (clock face test is where the patient is told to set the hands at a particular time. LBD patients not only have a harder time doing this, but a much harder time to draw the clock face and to center it on the page, typically off to a corner or edge. .
7. LBD patients are more given to clouding of consciousness and transient disturbances of consciousness, e.g. fluctuating cognition.
8. More men seem to have LBD, while more women are prone to AD.
9. Depression in LBD is more common than with AD.
10. Rapid Eye Movement (REM) sleep disorder is more common in LBD (patient truly believes his/her extra-real dreams are real).
11. Fewer neurofibrilliary tangles with LBD than AD. This is determined upon autopsy.
12. LBD patients appear to be more hypersensitive to medications than either AD or PD patients. There is a conflict between the cognition and Parkinsonism medications. Anti-psychotics drugs may work or may cause irreversible damage; could be fatal in long term.

1. 1) Shuffling gait (initially lack of heel/toe gait, shuffling, very short steps)
2. Severely bent posture, which Sinemet helps to correct, BUT can get worse and massage therapy may help.
3. Tremors in arms or legs.

Other symptoms that are PD-like:

1. Handwriting has become micrographic and almost impossible to read.
2. Tendency to falls - most definitely LBD - and helped with Physical Therapy and massage therapy.
3. Stiffness and rigidity that comes and goes.

1. Short-term memory almost always controlled by Aricept.
2. Confusion that comes and goes. Occasional sleep problems (the worst may be controlled by Remerom).
3. Tendency to be slow, stop and stand, not move until prompted.
4. Indecisiveness (DEFINITELY LBD).
5. Confused thinking that interferes with caregiver's efforts to attend to financial affairs.

Caregiver Site Research: A research project on the caregiver site found that most of our Loved One's have rhinitis (chronically runny nose).